Posted on Wednesday, November 12, 2008 - 01:09 pm:
Jos: I am at preliminary stages of veterinary attention, but wanted to ask if you would have any suggestions for good articles/websites on bizarre pregancies in equines.
Short version: Maiden mare foaled in April 2008. (She has always had prominant heat cycles and even after confirmed pregancy, exhibited heat cycles for 6 months. First pregnancy watched closely for possible twinning due to suspected multiple ovulation). Mare was exposed to stallion in May & June. Mare was turned out in early September (for weaning foal) with stallion. Developed mastistis late September, aborted what appeared to be two early pregancies (twinning). Later developed laminitis. Has continued to appear to cycle in and out of heat since mid-October. We have assumed she is open. However, upon follow-up field visit on her laminitis, veterinary team seems to believe she is showing pregnancy that would fit with a possible late April/May breeding. We have scheduled her for a US to try and figure out WHAT is going on with this mare!
Is it possible that a mare can take during a breeding and then, later continue to ovulate but not retain those pregnancies? If she did, let's just hypothetically say, ovulate in September multiple times, could she have aborted two and retained a third as a viable pregnancy? (Although my vets are very suspicious that this possible pregnancy is much further along than that.)
She has never been US before so we may find some sort of anomally that explains this bizarre circumstance so I don't want to jump to any conclusions on anything. I had tried to search the web for things such as multiple ovulation in equines and it is my understanding that it is rare (something like less than 1%) but some mares can triple and quadruple ovulate but there isn't a whole lot out there on viable pregnancies as a result of multiple ovulations to that extreme.
Would appreciate any information or direction you can provide. Thanks!
Posted on Wednesday, November 12, 2008 - 08:54 pm:
Here's some food for thought:
Pregnant mares ovulate. It's normal, and in fact is part of the early (up to 120 days) pregnancy maintenance mechanism.
When a mare aborts, the cervix (obviously) opens. The likelihood of a mare maintaining an additional single pregnancy after such an interruption of cervical competence is miniscule. To have her maintain a third pregnancy after aborting twins would be even "minisculer" (my word check hates that word!! ).
Some mares show estrus during pregnancy, hence turning her out with a stallion may result in her getting bred.
If a pregnant mare gets bred, she is likely to lose the existing pregnancy (as the cervix is interrupted by the stallion's penis). If this happens after the endometrial cups have regressed (typically around 90-120 days), she could return to a true estrus, and conceive if bred again.
Multiple ovulations are common - usually between 10 and 25% dependent upon breed, mare, and status (more common in barren mares).
Conception on multiple ovulations is common, although nature is good at reducing to a singleton pregnancy in many cases. It is however why we strongly recommend pregnancy checking with ultrasound (see the article about twinning on this site for more details - follow that link.
Thanks Jos. I appreciate your thoughts. I like the minisculer word, ha, that's pretty much where I was with this possibility; pretty convinced that this is perhaps something else going on versus a viable pregnancy at a possible 6 month gestation level after aborting what appeared to be "twin embryonic tissue" at a 30-45 day gestation level. I'm sure the US will be very useful in determining what in the world is going on here. LOL! If not, I may be on the front page of the National Enquirer!
Since we had gone through the "un-oh" last year of a possible twin pregnancy (that turned out single, thank goodness), we certainly had in mind for this mare to do early US during breeding to make sure we caught any possible twinning on this TB. We were fairly certain that she was barren so we didn't jump on the plan as we decided to leave her open until spring 2009 to let her health recover. This is certainly a mare that I think needs a bit more extensive workup to see what her breeding issues are for any future endeavors.
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